As an apparatus equipped with a rotating body such as a gear is run, there are cases in which continuous sounds continuously generated regardless of running state, non-continuous sounds generated in a particular running state, and vibrations not accompanying any sound are generated. Of these sounds and vibrations, teeth-contacting sounds generated due to rotation of gears with their teeth engaged with each other, and sounds generated from the rolling surface of a bearing (hereinafter, these sounds are called abnormal sounds) may be listed as non-continuous sounds. Conventionally, for the purpose of preventing such abnormal sounds from being generated, sensory inspection is carried out by an operator, or an apparatus for analyzing such abnormal sounds is developed.
An analyzing apparatus disclosed in Japanese Published Examined Patent Application No. 2596081 (pages 2 and 3, and FIG. 1) measures vibrations generated in response to rotation speeds in a predetermined range while varying the rotation speeds of gears, and picks up signals in a frequency range determined in response to the rotation speed and number of teeth of gears among signals obtained by analyzing the frequencies in connection with the vibrations. In accordance with the analyzing apparatus, the maximum value of abnormal noise is extracted.
Another analyzing apparatus, disclosed in Japanese Published Unexamined Patent Application No. 2002-257685 (paragraphs 0015 and 0016, and FIG. 4) simultaneously measures unevenness of rotation speeds when gears rotate, and acoustic pressure of sounds generated from the gears, and compares the waveforms of the respective signals. In accordance with the analyzing apparatus, it can be distinguished whether sounds being generated from a gear transmission having gears are resulting from gears or from other factors.
Still another analyzing apparatus, disclosed in Japanese Published Unexamined Patent Application No. 2001-194221 (paragraphs 0029 and 0030, and FIG. 13) picks up running sounds as data by attaching a sound collecting microphone and a recorder to a motorcycle, and identifies sounds of an already known volume, degree or order, whose ratio is comparatively high, among all sounds, using an order filter. In accordance with the analyzing apparatus, evaluation can be carried out based on the order of the sounds.
Incidentally, with conventional analyzing apparatuses, it is impossible to identify a place from which abnormal sounds being generated, if there is a plurality of rotating bodies. Also, even if an attempt is made to identify a place at which abnormal sounds being generated by way of sensory inspection, unevenness in results of sensory inspection is liable to occur because such a inspection is based on the sensitivity of a human being, and it is difficult to investigate the correlation between the results of the sensory inspection and the actually measured results. In particular, in a unit such as a transmission of an automobile, in which gears are disposed multi-axially on a rotating shaft, or multi-axial rotating shafts are incorporated, a number of places may be guessed to be the place where abnormal sounds are occurring, and it is difficult to identify the place of occurrence of the abnormal sounds.
In addition, with the conventional apparatuses, evaluation is carried out based on the elapsed time during a number of revolutions of a rotating body, and since the actual vehicle speed is different from the rotation speed of the rotating body when an object to be inspected such as an automobile moves, it is difficult to investigate the correlation of the results measured.
Further, in judgment based on maximum value as in the analyzing apparatus described in Japanese Published Examined Patent Application No. 2596081, if the volume of the abnormal sounds is low, it is not possible to detect the frequency even if it can be sensed by a human being.
The present invention has been developed to solve the above-described problems and shortcomings, and it is therefore an object of the invention to provide an analyzing apparatus that is capable of reliably distinguishing factors of sound generation and places thereof. Also, it is an object of the invention to provide an analyzing apparatus that is capable of reliably distinguishing factors of vibration generation even if vibrations are measured instead of sounds.